Policy makers, researchers, and clinicians agree that active parent involvement in treatment is critical to the effectiveness of child mental health services, in particular for children with disruptive behavior problems (DBPs). Parents often have difficulty attending and participating actively in treatment [labeled parent participatory engagement (PPE)], and a lack of PPE is linked to poorer child outcomes. The NIMH Child & Adolescent Services Research Program emphasizes research on family engagement and usual care settings, and the recent NIMH Strategic Plan highlights the importance of developing interventions that focus on treatment adherence (Strategy 3.2). This Mentored Patient-Oriented Career Development (K23) award is designed to provide the applicant with knowledge, skills, and pilot data necessary to launch an independent program of research to increase PPE and improve the effectiveness of public sector child mental health care. Through the training activities, the applicant will: 1) obtain mastery of existing PPE research and methods to develop PPE interventions using stakeholder feedback; 2) obtain training in a complementary set of transdisciplinary empirically-supported behavior change approaches selected to target PPE (social marketing/health communication, behavioral compliance and theory of planned behavior, Motivational Interviewing, patient activation); 3) gain a rich understanding of challenges in addressing PPE in a culturally diverse population; and 4) acquire skills in qualitative methods and multilevel modeling. The applicant will also receive training in the ethical conduct of research. The research plan is organized into two phases implemented with the support of the training plan and a team of mentors, consultants, and clinician and parent contributors. First, a multi-component, multi-media resource toolkit intervention will be developed to promote PPE in the treatment of children with DBPs. The proposed toolkit includes three parent tools to encourage PPE, three clinician tools that complement the parent tools to promote PPE, and several clinician training resources to support PPE and use of toolkit materials. The toolkit will draw on the behavior change approaches from the applicant's training to target a set of overlapping parent cognitive barrier/facilitator factors (motivation, expectations, perceived barriers, empowerment) and quality of care factors (participation in treatment planning, opportunities for ongoing participation, parent-clinician alliance) that are proposed mechanisms of change for improving PPE. Second, the toolkit's potential effectiveness to change parent cognitive barrier/facilitator and quality of care factors, PPE behaviors (attendance, active participation in sessions, adherence to recommendations between sessions), and child/family outcomes will be assessed by a pilot randomized controlled trial comparing the toolkit to a control condition (n=40 families within 10 clinicians for each condition). Toolkit feasibility, acceptability, and fidelity will also be assessed. Data will be used to design a larger scale R01 to test the toolkit's impact on PPE and child/family outcomes in public mental health settings.